Answer:
Step-by-step explanation:
Abstract
Malignant vascular tumors as part of the vascular anomalies spectrum are extremely rare in children and young adults. Instead, benign vascular neoplasias are frequently encountered in the pediatric patient population. While vascular malformations are congenital vascular lesions, originating from a mesenchymal stem cell defect, vascular tumors are neoplastic transformations of endothelial and other vascular cells. The appropriate differential diagnosis and nomenclature according to the classification of the International Society for the Study of Vascular Anomalies (ISSVA) is decisive to initiate correct therapy. While infantile hemangioma can be routinely diagnosed by clinical means and rarely require therapy, more rare vascular tumors are frequently difficult to diagnose, require dedicated cross-sectional imaging, and benefit from an interdisciplinary treatment approach. The focus of this review is to provide an overview over the spectrum of vascular tumors, typical imaging characteristics, and summarize treatment options including interventional radiology approaches.
Key points
Vascular tumors are distinct from vascular malformations and should be appropriately classified according to the classification of the International Society for the Study of Vascular Anomalies (ISSVA); misdiagnosis and inappropriate nomenclature is frequent.
Infantile hemangiomas are the most frequent vascular tumors in children and most frequently do not require treatment.
Locally aggressive as well as borderline tumors can present with typical imaging appearance depending on their degree of vascularity. Complications of benign vascular tumors include ulceration and bleeding which require immediate therapy, consisting of medical, surgical, and interventional radiology approaches.
Minimally invasive image-guided treatment strategies can be used for palliation and to manage complications.
Introduction
Vascular tumors comprise a vast spectrum of diseases and are therefore difficult to diagnose and classify. Benign vascular tumors can be mistaken for vascular malformations, but even more frequently vascular malformations are misdiagnosed as vascular tumors, such as infantile hemangiomas. Inappropriate misnomers and delayed diagnoses as well as false classification are responsible for wrong treatment approaches, which may delay appropriate therapy, or lead to significant morbidity and mortality. Herein, we discuss the differential diagnosis of vascular tumors from vascular malformations when appropriate; for an overview of the large spectrum of vascular malformations, we refer to recently published work [1,2,3,4].
Vascular tumors are characterized by a different pathobiology compared to vascular malformations. Vascular tumors are neoplastic, characterized by increased proliferation rates of endothelial and other vascular cells [5]. Instead, vascular malformations are congenital vascular lesions, grow commensurately with the child, cannot involute, and have abilities to expand hemodynamically. Vascular malformations demonstrate no neoplastic endothelial cell proliferation, contain small and large vascular channels lined by flat endothelium, have a unilamellar basement membrane, and have normal mast cell counts [1, 6,7,8].
Infantile hemangiomas initiate a rapid growth during the first months of life and regress spontaneously later on [9]. Congenital hemangiomas, much less frequent than infantile hemangiomas, can be divided into rapidly involuting congenital hemangioma (RICH), partially involuting congenital hemangiomas (PICH), and non-involuting congenital hemangiomas (NICH) due to their biological behavior after birth [10]. Most importantly, infantile hemangiomas rarely require imaging for correct diagnosis and similarly important, infantile hemangiomas rarely require aggressive treatment. Malignant vascular tumors instead exhibit a high metastatic potential similarly as in adults and thus require rapid diagnosis and therapy. In between benign and malignant vascular tumors, there is a specific group of tumors with locally aggressive behavior and potential risk of life-threatening coagulation disorders such as Kasabach-Merrit phenomenon seen in Tufted Angioma and Kaposiform Hemangioendothelioma [11]. These tumors are probably the most challenging to treat, and due to their rareness, no evidence-based guidelines and treatment strategies exist.